Contributions to general algebra 13 : proceedings of the 60th Workshop on General Algebra : "60. Arbeitstagung Allgemeine Algebra", University of Technology Dresden, June 22 - 25, 2000 and of the Summer School '99 on General Algebra and Ordered Sets, Velké Karlovice, August 30 - September 4, 1999 / ed. by I. Chajda ... [et al.]
